EIP 4844 (part 2)

Changelog.md

@@ -2,6 +2,7 @@
 
 Language Features:
  * Introduce global ``block.blobbasefee`` for retrieving the blob base fee of the current block.
+ * Introduce global function ``blobhash(uint)`` for retrieving versioned hashes of blobs, akin to the homonymous Yul builtin.
  * Yul: Introduce builtin ``blobbasefee()`` for retrieving the blob base fee of the current block.
  * Yul: Introduce builtin ``blobhash()`` for retrieving versioned hashes of blobs associated with the transaction.
 

docs/cheatsheet.rst

@@ -56,13 +56,16 @@ Members of ``address``
   returns ``false`` on failure
 - ``<address payable>.transfer(uint256 amount)``: send given amount of Wei to :ref:`address`, throws on failure
 
-.. index:: blockhash, block, block;basefee, block;blobbasefee, block;chainid, block;coinbase, block;difficulty, block;gaslimit, block;number, block;prevrandao, block;timestamp
+.. index:: blockhash, blobhash, block, block;basefee, block;blobbasefee, block;chainid, block;coinbase, block;difficulty, block;gaslimit, block;number, block;prevrandao, block;timestamp
 .. index:: gasleft, msg;data, msg;sender, msg;sig, msg;value, tx;gasprice, tx;origin
 
 Block and Transaction Properties
 ================================
 
 - ``blockhash(uint blockNumber) returns (bytes32)``: hash of the given block - only works for 256 most recent blocks
+- ``blobhash(uint index) returns (bytes32)``: versioned hash of the ``index``-th blob associated with the current transaction.
+  A versioned hash consists of a single byte representing the version (currently ``0x01``), followed by the last 31 bytes
+  of the SHA256 hash of the KZG commitment (`EIP-4844 <https://eips.ethereum.org/EIPS/eip-4844>`_).
 - ``block.basefee`` (``uint``): current block's base fee (`EIP-3198 <https://eips.ethereum.org/EIPS/eip-3198>`_ and `EIP-1559 <https://eips.ethereum.org/EIPS/eip-1559>`_)
 - ``block.blobbasefee`` (``uint``): current block's blob base fee (`EIP-7516 <https://eips.ethereum.org/EIPS/eip-7516>`_ and `EIP-4844 <https://eips.ethereum.org/EIPS/eip-4844>`_)
 - ``block.chainid`` (``uint``): current chain id

docs/units-and-global-variables.rst

@@ -74,6 +74,9 @@ Block and Transaction Properties
 --------------------------------
 
 - ``blockhash(uint blockNumber) returns (bytes32)``: hash of the given block when ``blocknumber`` is one of the 256 most recent blocks; otherwise returns zero
+- ``blobhash(uint index) returns (bytes32)``: versioned hash of the ``index``-th blob associated with the current transaction.
+  A versioned hash consists of a single byte representing the version (currently ``0x01``), followed by the last 31 bytes
+  of the SHA256 hash of the KZG commitment (`EIP-4844 <https://eips.ethereum.org/EIPS/eip-4844>`_).
 - ``block.basefee`` (``uint``): current block's base fee (`EIP-3198 <https://eips.ethereum.org/EIPS/eip-3198>`_ and `EIP-1559 <https://eips.ethereum.org/EIPS/eip-1559>`_)
 - ``block.blobbasefee`` (``uint``): current block's blob base fee (`EIP-7516 <https://eips.ethereum.org/EIPS/eip-7516>`_ and `EIP-4844 <https://eips.ethereum.org/EIPS/eip-4844>`_)
 - ``block.chainid`` (``uint``): current chain id

docs/using-the-compiler.rst

@@ -178,6 +178,7 @@ at each version. Backward compatibility is not guaranteed between each version.
    - Smaller code size and gas savings due to the introduction of ``push0`` (see `EIP-3855 <https://eips.ethereum.org/EIPS/eip-3855>`_).
 - ``cancun``
    - The block's blob base fee (`EIP-7516 <https://eips.ethereum.org/EIPS/eip-7516>`_ and `EIP-4844 <https://eips.ethereum.org/EIPS/eip-4844>`_) can be accessed via the global ``block.blobbasefee`` or ``blobbasefee()`` in inline assembly.
+   - Introduces ``blobhash()`` in inline assembly and a corresponding global function to retrieve versioned hashes of blobs associated with the transaction (see `EIP-4844 <https://eips.ethereum.org/EIPS/eip-4844>`_).
 
 .. index:: ! standard JSON, ! --standard-json
 .. _compiler-api:

libsolidity/analysis/GlobalContext.cpp

@@ -59,17 +59,18 @@ int magicVariableToID(std::string const& _name)
 	else if (_name == "tx") return -26;
 	else if (_name == "type") return -27;
 	else if (_name == "this") return -28;
+	else if (_name == "blobhash") return -29;
 	else
 		solAssert(false, "Unknown magic variable: \"" + _name + "\".");
 }
 
-inline std::vector<std::shared_ptr<MagicVariableDeclaration const>> constructMagicVariables()
+inline std::vector<std::shared_ptr<MagicVariableDeclaration const>> constructMagicVariables(langutil::EVMVersion _evmVersion)
 {
 	static auto const magicVarDecl = [](std::string const& _name, Type const* _type) {
 		return std::make_shared<MagicVariableDeclaration>(magicVariableToID(_name), _name, _type);
 	};
 
-	return {
+	std::vector<std::shared_ptr<MagicVariableDeclaration const>> magicVariableDeclarations = {
 		magicVarDecl("abi", TypeProvider::magic(MagicType::Kind::ABI)),
 		magicVarDecl("addmod", TypeProvider::function(strings{"uint256", "uint256", "uint256"}, strings{"uint256"}, FunctionType::Kind::AddMod, StateMutability::Pure)),
 		magicVarDecl("assert", TypeProvider::function(strings{"bool"}, strings{}, FunctionType::Kind::Assert, StateMutability::Pure)),
@@ -101,11 +102,19 @@ inline std::vector<std::shared_ptr<MagicVariableDeclaration const>> constructMag
 			FunctionType::Options::withArbitraryParameters()
 		)),
 	};
+
+	if (_evmVersion >= langutil::EVMVersion::cancun())
+		magicVariableDeclarations.push_back(
+			magicVarDecl("blobhash", TypeProvider::function(strings{"uint256"}, strings{"bytes32"}, FunctionType::Kind::BlobHash, StateMutability::View))
+		);
+
+	return magicVariableDeclarations;
 }
 
 }
 
-GlobalContext::GlobalContext(): m_magicVariables{constructMagicVariables()}
+GlobalContext::GlobalContext(langutil::EVMVersion _evmVersion):
+	m_magicVariables{constructMagicVariables(_evmVersion)}
 {
 }
 

libsolidity/analysis/GlobalContext.h

@@ -23,6 +23,7 @@
 
 #pragma once
 
+#include <liblangutil/EVMVersion.h>
 #include <libsolidity/ast/ASTForward.h>
 #include <map>
 #include <memory>
@@ -47,7 +48,7 @@ class GlobalContext
 	GlobalContext(GlobalContext const&) = delete;
 	GlobalContext& operator=(GlobalContext const&) = delete;
 
-	GlobalContext();
+	GlobalContext(langutil::EVMVersion _evmVersion);
 	void setCurrentContract(ContractDefinition const& _contract);
 	void resetCurrentContract() { m_currentContract = nullptr; }
 	MagicVariableDeclaration const* currentThis() const;

libsolidity/ast/Types.cpp

@@ -3075,6 +3075,7 @@ std::string FunctionType::richIdentifier() const
 	case Kind::ABIEncodeCall: id += "abiencodecall"; break;
 	case Kind::ABIEncodeWithSignature: id += "abiencodewithsignature"; break;
 	case Kind::ABIDecode: id += "abidecode"; break;
+	case Kind::BlobHash: id += "blobhash"; break;
 	case Kind::MetaType: id += "metatype"; break;
 	}
 	id += "_" + stateMutabilityToString(m_stateMutability);

libsolidity/ast/Types.h

@@ -1270,6 +1270,7 @@ class FunctionType: public Type
 		SetGas, ///< modify the default gas value for the function call
 		SetValue, ///< modify the default value transfer for the function call
 		BlockHash, ///< BLOCKHASH
+		BlobHash, ///< BLOBHASH
 		AddMod, ///< ADDMOD
 		MulMod, ///< MULMOD
 		ArrayPush, ///< .push() to a dynamically sized array in storage

libsolidity/codegen/ExpressionCompiler.cpp

@@ -1035,9 +1035,13 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			break;
 		}
 		case FunctionType::Kind::BlockHash:
+		case FunctionType::Kind::BlobHash:
 		{
 			acceptAndConvert(*arguments[0], *function.parameterTypes()[0], true);
-			m_context << Instruction::BLOCKHASH;
+			if (function.kind() == FunctionType::Kind::BlockHash)
+				m_context << Instruction::BLOCKHASH;
+			else
+				m_context << Instruction::BLOBHASH;
 			break;
 		}
 		case FunctionType::Kind::AddMod:

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -1498,11 +1498,13 @@ void IRGeneratorForStatements::endVisit(FunctionCall const& _functionCall)
 	case FunctionType::Kind::GasLeft:
 	case FunctionType::Kind::Selfdestruct:
 	case FunctionType::Kind::BlockHash:
+	case FunctionType::Kind::BlobHash:
 	{
 		static std::map<FunctionType::Kind, std::string> functions = {
 			{FunctionType::Kind::GasLeft, "gas"},
 			{FunctionType::Kind::Selfdestruct, "selfdestruct"},
 			{FunctionType::Kind::BlockHash, "blockhash"},
+			{FunctionType::Kind::BlobHash, "blobhash"},
 		};
 		solAssert(functions.find(functionType->kind()) != functions.end());
 

libsolidity/interface/CompilerStack.cpp

@@ -235,6 +235,9 @@ void CompilerStack::setEVMVersion(langutil::EVMVersion _version)
 	if (m_stackState >= ParsedAndImported)
 		solThrow(CompilerError, "Must set EVM version before parsing.");
 	m_evmVersion = _version;
+	// GlobalContext depends on evmVersion since the Cancun hardfork.
+	// Therefore, we reset it whenever we set a new EVM version, ensuring that the context is never reused with a mismatched version.
+	m_globalContext.reset();
 }
 
 void CompilerStack::setEOFVersion(std::optional<uint8_t> _version)
@@ -469,7 +472,7 @@ bool CompilerStack::analyze()
 			if (source->ast && !syntaxChecker.checkSyntax(*source->ast))
 				noErrors = false;
 
-		m_globalContext = std::make_shared<GlobalContext>();
+		m_globalContext = std::make_shared<GlobalContext>(m_evmVersion);
 		// We need to keep the same resolver during the whole process.
 		NameAndTypeResolver resolver(*m_globalContext, m_evmVersion, m_errorReporter, experimentalSolidity);
 		for (Source const* source: m_sourceOrder)

scripts/test_antlr_grammar.sh

@@ -128,6 +128,7 @@ done < <(
       grep -v -E 'inlineAssembly/prevrandao_disallowed_function_post_paris.sol' |
       # Skipping a test with "let blobhash := ..."
       grep -v -E 'inlineAssembly/blobhash_pre_cancun.sol' |
+      grep -v -E 'inlineAssembly/blobhash_pre_cancun_not_reserved.sol' |
       # Skipping license error, unrelated to the grammar
       grep -v -E 'license/license_double5.sol' |
       grep -v -E 'license/license_hidden_unicode.sol' |

test/libsolidity/Assembly.cpp

@@ -63,7 +63,7 @@ evmasm::AssemblyItems compileContract(std::shared_ptr<CharStream> _sourceCode)
 
 	Scoper::assignScopes(*sourceUnit);
 	BOOST_REQUIRE(SyntaxChecker(errorReporter, false).checkSyntax(*sourceUnit));
-	GlobalContext globalContext;
+	GlobalContext globalContext(solidity::test::CommonOptions::get().evmVersion());
 	NameAndTypeResolver resolver(globalContext, solidity::test::CommonOptions::get().evmVersion(), errorReporter, false);
 	DeclarationTypeChecker declarationTypeChecker(errorReporter, solidity::test::CommonOptions::get().evmVersion());
 	solAssert(!Error::containsErrors(errorReporter.errors()), "");

test/libsolidity/SolidityExpressionCompiler.cpp

@@ -42,6 +42,7 @@
 
 using namespace solidity::evmasm;
 using namespace solidity::langutil;
+using namespace solidity::test;
 
 namespace solidity::frontend::test
 {
@@ -124,7 +125,7 @@ bytes compileFirstExpression(
 
 	ErrorList errors;
 	ErrorReporter errorReporter(errors);
-	GlobalContext globalContext;
+	GlobalContext globalContext(solidity::test::CommonOptions::get().evmVersion());
 	Scoper::assignScopes(*sourceUnit);
 	BOOST_REQUIRE(SyntaxChecker(errorReporter, false).checkSyntax(*sourceUnit));
 	NameAndTypeResolver resolver(globalContext, solidity::test::CommonOptions::get().evmVersion(), errorReporter, false);
@@ -656,6 +657,28 @@ BOOST_AUTO_TEST_CASE(blockhash)
 	BOOST_CHECK_EQUAL_COLLECTIONS(code.begin(), code.end(), expectation.begin(), expectation.end());
 }
 
+BOOST_AUTO_TEST_CASE(
+	blobhash,
+	*boost::unit_test::precondition(minEVMVersionCheck(EVMVersion::cancun()))
+)
+{
+	char const* sourceCode = R"(
+		contract test {
+			function f() public {
+				blobhash(3);
+			}
+		}
+	)";
+
+	bytes code = compileFirstExpression(sourceCode, {}, {});
+
+	bytes expectation({
+		uint8_t(Instruction::PUSH1), 0x03,
+		uint8_t(Instruction::BLOBHASH)
+	});
+	BOOST_CHECK_EQUAL_COLLECTIONS(code.begin(), code.end(), expectation.begin(), expectation.end());
+}
+
 BOOST_AUTO_TEST_CASE(gas_left)
 {
 	char const* sourceCode = R"(

test/libsolidity/ViewPureChecker.cpp

@@ -53,6 +53,8 @@ BOOST_AUTO_TEST_CASE(environment_access)
 	};
 	if (solidity::test::CommonOptions::get().evmVersion().hasStaticCall())
 		view.emplace_back("address(0x4242).staticcall(\"\")");
+	if (solidity::test::CommonOptions::get().evmVersion().hasBlobHash())
+		view.emplace_back("blobhash(7)");
 
 	// ``block.blockhash`` and ``blockhash`` are tested separately below because their usage will
 	// produce warnings that can't be handled in a generic way.

test/libsolidity/semanticTests/builtinFunctions/blobhash.sol

@@ -0,0 +1,18 @@
+contract C {
+    function f() public view returns(bytes32) {
+        return blobhash(0);
+    }
+    function g() public view returns(bytes32) {
+        return blobhash(1);
+    }
+    function h() public view returns(bytes32) {
+        // NOTE: blobhash(2) should return 0 since EVMHost has only two blob hashes injected in the block the transaction is being executed.
+        return blobhash(2);
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// f() -> 0x0100000000000000000000000000000000000000000000000000000000000001
+// g() -> 0x0100000000000000000000000000000000000000000000000000000000000002
+// h() -> 0x00

test/libsolidity/semanticTests/builtinFunctions/blobhash_shadow_resolution.sol

@@ -0,0 +1,12 @@
+contract C {
+    function blobhash(uint256 index) public pure returns(bytes32) {
+        return bytes32(index);
+    }
+    function f() public pure returns(bytes32) {
+        return blobhash(3);
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// f() -> 0x03

test/libsolidity/semanticTests/state/blobhash.sol

@@ -0,0 +1,14 @@
+contract C {
+    function f(uint _index) public returns (bytes32) {
+        return blobhash(_index);
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// f(uint256): 0 -> 0x0100000000000000000000000000000000000000000000000000000000000001
+// f(uint256): 1 -> 0x0100000000000000000000000000000000000000000000000000000000000002
+// f(uint256): 2 -> 0x00
+// f(uint256): 255 -> 0x00
+// f(uint256): 256 -> 0x00
+// f(uint256): 257 -> 0x00

test/libsolidity/semanticTests/state/uncalled_blobhash.sol

@@ -0,0 +1,12 @@
+contract C {
+    function f() public returns (bytes32) {
+        // NOTE: The `tx_context.blob_hashes` is injected into EVMHost with the following hashes, indexed accordingly:
+        // 0 -> 0x0100000000000000000000000000000000000000000000000000000000000001
+        // 1 -> 0x0100000000000000000000000000000000000000000000000000000000000002
+        return (blobhash)(0);
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// f() -> 0x0100000000000000000000000000000000000000000000000000000000000001

test/libsolidity/syntaxTests/globalFunctions/blobhash_function_pre_cancun.sol

@@ -0,0 +1,11 @@
+contract C {
+    function blobhash(uint256 index) public pure returns(bytes32) {
+        return bytes32(index);
+    }
+    function f() public pure returns(bytes32) {
+        return blobhash(2);
+    }
+}
+// ====
+// EVMVersion: <=shanghai
+// ----

test/libsolidity/syntaxTests/globalFunctions/blobhash_function_shadow_warning.sol

@@ -0,0 +1,12 @@
+contract C {
+    function blobhash(uint256 index) public pure returns(bytes32) {
+        return bytes32(index);
+    }
+    function f() public pure returns(bytes32) {
+        return blobhash(2);
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// Warning 2319: (17-117): This declaration shadows a builtin symbol.

test/libsolidity/syntaxTests/globalFunctions/blobhash_no_call.sol

@@ -0,0 +1,10 @@
+contract C
+{
+    function f() public pure {
+        blobhash;
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// Warning 6133: (52-60): Statement has no effect.

test/libsolidity/syntaxTests/globalFunctions/blobhash_not_declared_pre_cancun.sol

@@ -0,0 +1,10 @@
+contract C
+{
+    function f() public pure {
+        blobhash;
+    }
+}
+// ====
+// EVMVersion: <=shanghai
+// ----
+// DeclarationError 7576: (52-60): Undeclared identifier. Did you mean "blockhash"?

test/libsolidity/syntaxTests/globalFunctions/blobhash_var_pre_cancun.sol

@@ -0,0 +1,9 @@
+contract C {
+    function f() public pure returns (bool) {
+        bool blobhash = true;
+        return blobhash;
+    }
+}
+// ====
+// EVMVersion: <=shanghai
+// ----

test/libsolidity/syntaxTests/globalFunctions/blobhash_var_shadow_warning.sol

@@ -0,0 +1,11 @@
+contract C
+{
+    function f() public pure returns (bool) {
+        bool blobhash = true;
+        return blobhash;
+    }
+}
+// ====
+// EVMVersion: >=cancun
+// ----
+// Warning 2319: (67-80): This declaration shadows a builtin symbol.

test/libsolidity/syntaxTests/inlineAssembly/blobhash_pre_cancun_not_reserved.sol

@@ -0,0 +1,19 @@
+contract C {
+    function f() public pure returns (uint ret) {
+        assembly {
+            let blobhash := 1
+            ret := blobhash
+        }
+    }
+    function g() public pure returns (uint ret) {
+        assembly {
+            function blobhash() -> r {
+                r := 1000
+            }
+            ret := blobhash()
+        }
+    }
+}
+// ====
+// EVMVersion: <=shanghai
+// ----